1. Fungi
Chapter 31

2. Plantae Fungi Animalia
Protista
Monera

3. Kingdom Fungi Uses: medicine food Ecological value: major decomposers
About 100,000 species
Uses:
medicine
food
Ecological value:
major decomposers
symbiotic relationships (N2 fixers)
Problems:
some strains are deadly
athletes foot
destroy library books
destroy crops

4. Some fungi are pathogens
About 30% of the 100,000 known species of fungi are parasites, mostly on or in plants.
American elms:
Dutch Elm Disease
American chestnut:
chestnut blight
What is DED, and where did it come from? DED is one of the most destructive shade tree diseases that affects elm trees. The disease kills individual branches and eventually the entire tree within one to several years. A fungus and an insect are responsible for DED development. The fungus was introduced to the United States on diseased logs from Europe in the 1930’s. What causes the tree to die from DED? The DED fungus grows and reproduces in the water conducting parts of elm branches and stems. The fungus blocks water movement to tree leaves which causes the leaves to wilt and turn brown. How does the DED fungus get into the tree? The fungus needs help from insects, the elm bark beetles. Elm bark beetles use weakened and diseased trees to reproduce. Beetle offspring emerge from diseased elms and fly to healthy elms to feed. However, before leaving diseased trees, spores of the DED fungus (which are like tiny fungus “seeds”) attach onto them. When these fungus-infested beetles feed on healthy tree branches, they make small wounds in the wood, and the fungus enters the branch directly through these wounds. Once the fungus is in an elm tree, it can move through the root system of a diseased tree into the root system of adjacent healthy elm trees. It can do this because roots of elm trees growing close to each other frequently join or graft to each other. United States Department of Agriculture Forest Service Northeastern Area NA-PR Page 2How can I tell if an American elm has DED? Look for leaves that are wilting or yellow and which eventually turn brown. Wilting and leaf color change are symptoms of DED that occur during the spring and summer, but usually start to appear one month after trees leaf out in the spring. Leaves most affected appear at the end of large branches. Dead branches without leaves may indicate previous year’s mortality from DED. In some communities, disease experts make routine elm examinations for DED symptoms. How and why do experts evaluate DED symptoms?Experts examine each tree and estimate the percent of leaves with symptoms and relate this percentage to where symptoms are located. This determines how much disease is in the tree, and it can also indicate whether the fungus infected the tree through joined roots or bark beetle wounds. The most appropriate DED management tactics are based on the amount of disease present. The amount of disease can be described simply as being either minor or major. What are minor amounts of DED in elms and can these elms be treated? Elms with minor DED have few symptoms (less than 10 percent of all leaves) usually located in only one large branch. DED may be eliminated from these trees by pruning out diseased branches and/or injecting chemical fungicide into the base of the trees. If left untreated, however, the amount of disease will increase. What are major amounts of DED in elms and can these elms be treated? Elms with major DED usually have more than 10 percent of all leaves or more than one large branch showing symptoms. Unfortunately trees with major amounts of disease cannot be effectively pruned. Fungicide injection is unlikely to be effective to stop an infection that has occurred through joined roots or which has affected a large portion of the branches. Elms with major amounts of disease will eventually die from the disease, and provide habitat for beetles and fungi that can infect healthy trees. Elms with major DED should be removed as soon as possible. This removal of diseased elms is called sanitation and is crucial to eliminate the spread of both the elm bark beetles and fungus to healthy neighboring elms. Is there hope for the American elm? Yes. If communities practice good sanitation (removal of dead trees), many existing elms will escape DED infection. It is also possible to prune diseased branches and inject individual high-value elms with fungicides to treat and protect them from DED infection. Also, scientists are now testing American elms that may be tolerant or resistant to DED. Combining all of these management tactics provides promise for the continued presence of American elms in our cities and parks. Where can I get more information about DED? The recent publication “How to Identify and Manage Dutch Elm Disease” is now available on the Internet at Information is also available from your city forester, tree care companies, your local Cooperative Extension Service, or the Forest Service offices listed below. Photographs provided by Dr. R. Jay Stipes, Virginia Polytechnic Institute and State University. For additional information, contact: Linda Haugen USDA Forest Service 1992 Folwell Avenue St. Paul, MN Alan Iskra USDA Forest Service 180 Canfield Street Morgantown, WV Phone (304) July 1999
Was once one of America's most dominant trees

5. Some fungi are pathogens
Other fungi, such as rusts and ergots, infect grain crops, causing tremendous economic losses each year.

6. Some fungi are pathogens
                              
Curse of the Mummy

7. Some fungi are persistant
Athletes Foot

8. Kingdom Fungi Eukaryotic, absorptive
Mostly multicellular (except few, e.g. yeast)
Heterotrophic (decomposers & parasitic)
Mycelium (body of hyphae)

9. Kingdom Fungi Firm cell walls (generally of “chitin”)
“Spores” as reproductive bodies
Unique chromosomes and nuclei
Includes molds, yeasts, rusts, and mushrooms

11. hyphae - the vegetative bodies of most fungi, constructed of tiny filaments
mycelium -an interwoven mat of hyphae

12. Human hair
Fungal hypha

13. Septate hypha:
multicellular
walls divided by septa
Ceonocytic hypha:
continuous cytoplasm mass
multinucleate
no septa

14. Haustoria:
Modified hyphae found in parasitic fungi
Function: absorb nutrients from host
Some fungi even have hyphae adapted for preying on animals.

15. Kingdom Fungi Division Chytridiomycota Division Ascomycota
Division Basidiomycota
Division Zygomycota
Division Deuteromycota

16. ?
Deuteromycota
Fungus-like protist

17. The four fungal phyla can be distinguished by their reproductive features.

18. Division Chytridiomycota
mainly aquatic.
Some are saprobes, while others parasitize protists, plants, and animals.
chitinous cell wall
flagellated zoospores
the most primitive fungi

19. Division Zygomycota “Zygote fungi” (bread molds)
Zygote = “mated” hyphal strands
Live in soil, water
Some are parasites
600 species

20. Mated hyphal strands

22. The zygosporangia are resistant to freezing and drying.
When conditions improve, the zygosporangia release haploid spores that colonize new substrates.
Pilobolus aiming its spores.

23. The zygomycete Rhizopus can reproduce either asexually or sexually.

24. Division Ascomycota “Sac fungi” (truffles, yeast)
Beer > 6,000 years
Wine > 8,000 years
Lichens
Decomposers, pathogens
“yeast” describes a form of fungi (i.e., non-hyphal)
60,000 species

25. Division Ascomycota
Scarlet cup
Morchella
truffles

26. Division Ascomycota
Close up of cheese showing blue-green mycelium of Penicillium roqueforti.
Roquefort cheese

27. Yeast

28. Lichen

29. Lichen Anatomy

30. Ascomycetes are characterized by an extensive heterokaryotic stage during the formation of ascocarps.

31. Division Basidiomycota
“Club fungi” (mushrooms)
Club-shaped reproductive structure
Food
Plant diseases
25,000 species

34. Fairy Ring

35. The life cycle of a club fungus usually includes a long-lived dikaryotic mycelium.

36. Division Deuteromycota
“Imperfect fungi” (penicillin)
Unrelated group
Asexual
No info on sexual cycle
25,000 species

37. Penicillin
Woops…
now Ascomycota

38. Candida albicans
“yeast infection”

39. Botrytis: “Noble Rot”

40. Plant-Fungal Relationships
Mycorrhizae (“fungus roots”)
90% of tree species have this association
Very important to absorption of water and nutrients

41. Soil surface
Plant roots
Mycorrhizae
Increases s.a. for absorption